So William Cullom Bates (1856-1937) owned Square 551 lot 857 and at one time the confusing lot that sat on old lots 7 & 8. He and his wife Linnie/Melinda Bell Martin Bates (1859-1935) sold that to Novella F. Gibson. I can’t really tell where lot 857 is but a 1940 deed, selling the property, used to be 213 Q St NW. But looking at a map, a property sitting on 7 & 8 is 215 Q St NW.
In 1935, before they both died, they lived at 5712 Colorado Ave NW. In 1930 Mr. Bates was listed as retired but before that he was a salesman. Nothing special. If I was more sure about the address, I would take a guess of what he was doing with the property, as square 551 had commercial elements.